Electrophotographic developing unit



March 5, 1963 K. M. OLIPHANT ELECTROPHOTOGRAPHIC DEVELOPING UNIT 2 Sheets-Sheet 1 Filed March 16, 1961 INVENTOR.

March 5, 1963 K. M. OLIPHANT ELECTROPHOTOGRAPHIC DEVELOPING UNIT 2 Sheets-She et 2 Filed March 16, 1961 4 /NVENTOR.

KEITH MER\D\TH OUPHANT EL5I United States Patent Ofifice 3,079,890 Patented Mar. 5, 1963 3,079,890 ELECTROPHOTOGRAPHIC DEVELOPING UNIT Keith Meredith Oliphant, Westbourue Park, South Australia, Australia, assignor to Research Laboratories of Australia Limited, Adelaide, South Australia, Australia Filed Mar. 16, 1961, Ser. No. 96,191 Claims priority, application Australia Mar. 17, 1960 7 Claims. (Cl. 118-637) This invention relates to an electrophotographic developing unit and in particular it relates to a unit which will develop a Xerographic image by use of a liquid developer.

Liquid development can be carried out in various ways such as by having a body of the liquid developer in a tray and submerging the paper or the like containing the electrostatic image thereon, or the liquid can be poured over the image or can be carried over by means of a roller to which the developer liquid is applied.

It is, however, desirable to have a unit which can effect development in a simple manner without exposing large quantities of this liquid and prefer-ably without wetting the back of the paper or the like which is being developed.

The present invention attains this object by providing a unitzwherein developer is caused to flow over the paper or the like being developed and the developer is recirculated, the improvements comprising a near vertical sloping support, means to hold the paper or the like on the support, a nozzle at the top of the support movable along the support to direct developer over the support, a trough at the base of the support to receive developer flowing over the support, and means to pump developer from the trough to the nozzle. A bleed system is preferably used for the developer to control the quantity flowing over the support.

Obviously such an invention can be considerably varied in its constructional details, but to enable the invention to be fully understood an embodiment ofsarne will now be described with reference to the accompanying drawings, in which:

': FIG. 1 is a perspective view of the developer unit, the

subject of the embodiment,

FIG. 2 is a schematic view showing the operation of the unit,

FIG. 3 is a rear elevation of the developing unit with the case in section, FIG. 4 is a transverse section of the machine on line 4-4 of FIG. 3,

FIG. 5 is an enlarged section of-the upper part of the unit,

FIG. 6 is an enlarged sectional view showing the drive forthe nozzle,

FIG. 7 is a transverse section of the pump, and

FIG. 8 is a section of the flow control valve.

A case 1 carries a sloping support 2 for the material to be developed, the support 2 having at its top a pair of clips 3 arranged to receive the upper edge of the sheet of material 5-which is to be developed.

The support 2 slopes forwardly towards its bottom edge 6 but is in a near vertical position.

At the base of the support 2 is a trough 7 so arranged that developer flowing down the support 2 will be received in this trough 7. I v

Supported on horizontal runways 9 parallel to the upper edge of the support 2 on which development is effected, is a nozzle 10, the actual position of the nozzle 10 being such that liquid flowing from the nozzle 10 will be projected on to the matter such as the sheet 5 which is held on the support 2 and will flow over the sheet down into the trough 7. The lines 11 in FIG. 2 indicate the path of liquid flow. To feed the liquid to the nozzle 10,

a pump 14 is provided which comprises a hollow body having within it a diaphragm 15 coupled by means of an operating stem 16 to a lever 17 which is pivoted to a bracket 18 at one end and is coupled by means of a connecting rod 19 at the other end to a crank 20 on a pulley 21 on a shaft 22. The pulley 21 is driven from a motor 23 by a belt 24.

Liquid which is moved by the pump 14 is drawn from the trough 7 through the pipe 25 to a valve housing 26 through a non-return valve 27, the pump being connected to the valve housing 26 by means of the pipe 28.

The valve housing 26 is also connected by means of a non-return valve 29 to a hose 30 leading to the nozzle 10, the valve housing 26 having in it a strainer 31 so disposed that as the pump 14 is operated, liquid is drawn from the trough 7 through the pipe 25 and is then supplied to the hose 30 leading to the nozzle.

To control the flow of the developer fluid to the nozzle 10, a branch pipe 33 is provided which leads from the hose 30 leading to the trough 7 and has a tap 34 on its end which is normally open so that the pump will supply the liquid back to the trough 7 to keep the liquid in the trough constantly circulating, but when it is desired to supply liquid to the nozzle 10, the tap 34 is closed and the liquid will then flow through the hose 30 to the nozzle.

To control the movement of the nozzle 10 along its track 9 a chain 35 passes around idler pulleys 36 and thence around a sprocket 37 on a shaft 38 which can be driven in either direction by manipulating a lever 39 projecting from the front of the unit, the lever being pivoted on a support 40 and having its end connected to a swinging arm 41 which in turn is pivoted on a support 42, this arm 41 having in it a bearing 43 which carries the shaft 38 on which the sprocket 37 is mounted.

On the shaft 38 is a roller 45 of resilient material which is adapted to engage either a roller 46 on one side of it or a roller 47 on the other side of it, these rollers 46 and 47 being connected together by means of gear wheels 48 so that they rotate in opposite direction. The shaft 50 of one of the rollers has a pulley 51 on it which is coupled by means of a belt 52 to a pulley 53 on the aforesaid shaft 22 which is driven by the motor 23.

By means of this arrangement when the lever 39 is in a central position no drive takes place to the nozzle 10, but when the lever 39 is moved either to the right or the left to bring the roller 45 on the movable shaft 38 into contact with either of the driven rollers 46 or 47, the chain 35 is appropriately moved and the nozzle 10 is therefore driven in the required direction.

This arrangement allows the nozzle 10 to be moved across the sheet 5 which is being developed or it can be stopped at any place where more intensive develop ment is required, or can be moved back and forth any number of times if the image is to be subjected .to longer development.

The control of the liquid is of course also a veryfine one as the tap 34 can be turned to give any required amount of bleed from the hose 30 going to the nozzle 10 back to the trough 7 and thus the quantities at all times are under full control.

The support 2 on which development takes place has as said a pair of clips 3 at its upper edge under which the paper or the like to be developed is placed to hold same in position, but this support 2 instead of being simply fixed to the case 1 is itself movable in a side to side direction by having on the support short stub shafts 55 which have on them grooved wheels 56 which in turn engage horizontally placed bars 57, the arrangement being such that a short movement from side to side may be given to the support 2.

To so move the support 2, a crank pin 60 is provided on a pulley 61 which is carried on a shaft 62 supported from a frame 63, the pulley being driven by means of a belt 64 from a motor 65. The pin 60 engages a bracket 66 connected to the support 2.

In this way the support 2 can be oscillated from side,

to side as the motor 65 revolves the pulley 61, this action serving to distribute the developer uniformly over the face of the support 2 and thus improving the action by destroying channelling of the liquid which could otherwise t'ake place if it were simply allowed to flow over a stationary surface.

As the developers may'have a volatile nature, the unit is provided with a cover 68 having a glass front '69 through which development can be watched, the cover being carried by hinges 70 along its top and provided with a pair of telescopic friction arms 71 pivoted to the cover and to the frame which allow the cover to be moved to an open or raised position and will hold it in that cality.

The outlet 72 at the top is for the purpose of applying suction to the inside of the case 1 if such is required to draw ofl volatile vapours.

In this way when it is desired to develop an electrostatic image on a photoconductor surface or other face medium, the medium is simply clipped or held to the developer support 2 and the developer is caused to flow over it by moving the nozzle 10 a distance such that the actual width of the image will be covered by the developer.

As the image is developed immediately in front of the operator, and as he can move thenozzle 10 back and forth across the top of the support 2, it is possible for him to closely watch the development taking place and to regulate the flow of any particular locality by appropriately moving the nozzle, this being found very desirable in xerographic development.

The nozzle 10 can, if desired, be flat in a horizontal plane so that a thin horizontal jet of liquid is projected on to the image, and the distance of the end of the nozzle quantity of fluid developer j said case; a nozzle, mounted on said runways for dis- 10 from the support 2 need only be slight as the pressure of the liquid can be quite low, it being necessary only to project it on to the top of the image area and the liquid will then flow down under gravity into the receiving trough 7 at the bottom.

The fact that the support 2is in a near vertical position ensuresthat little space is taken in a dark room or wherever the unit is situated, the invention avoiding the use of trays with their bulk, and generally facilitating xerographic development by giving a full and adequate control under full view and under exact regulation of the operator.

What I claim is:

1. An improved xerographic developer u'nit comprising: a nearly vertical supp'ortmember; means to hold an image sheet, having a latent charge image thereon, on said support member; a nozzle, located at the top of said support member, for discharging a fluid developer onto an image sheet supported on said support member; means for moving said nozzle across the top of said support member to distribute fluid developer across the entire surface of said sheet and develop said image; a reservoir "trough for storing "a supply 'of a fluid developer, disposed at the bottom of said support member in position "to receive arid store excess developer flowing downwardly from said support member; pump means 'for recirculating developer from said trough to "said nozzle; and 'flow control'mean's to regulate the flow of developer through -said nozzle.

2. An improved xerographic developer unit according to claim 1,.in which said flow control means includes a branch conduit extending-from .the outlet of the pump means to the trough, and valve means in the branch con- -duit to control diversion of fluid developer back to the charging a fluid developer onto an image sheet supported on said support member, said nozzle being movable along said runways to distribute fluid developer across the entire surface of said sheet and develop said image; means, mounted on said case and connected to said nozzle, for moving said nozzle back and forth along said runways; a reservoir trough for storing a supply of a fluid developer, disposed at the bottom of said support member in position to receive and store excess developer flowing downwardly from said support member; pumprmeans having an outlet connected through a flexible tube to said nozzle and an inlet connected to said trough, for recirculating fluid developer from said trough to said nozzle; a branch conduit from said tube back to said trough; and flow control means, in said branch conduit, to regulate the flow of fluid developer back to said trough and thereby regulate the flow through said nozzle.

5. An improved xerographic developer unit according to claim 4, further comprising horizontally extending bars mounted on said case, means for slidably mounting said support member on said bars, and means for reciprocating said support member from side to side on said bars during development.

6. An improved xerographic developer unit comprising: a nearly vertical support member; means to hold an image sheet, having an electrostatic charge image thereon, on said support member; horizontal runways extending across the top of said support member; anozzle, mounted on said runways for movement therealong, for discharging a fluid developer onto an image sheet supported on said support member; flexible drive means extending across said support member in parallel relation to said runways and engaged with said nozzle; a pair of oppositely driven rolls; means for alternately connecting said rollers in driving relation to said drive means to move said nozzle across the top of said support member and distribute fluid developer across the entire surface of said sheet; a reservoir trough forjstoring a supply of a fluid developer, disposed at the bottomof said support member in position to receive and store excess developer flowing downwardly from said support member; pump means for recirculating fluid-developer from said trough to said nozzle; and flow control means to regulate the flow of fluid developer through' said nozzle.

7. An improved xerographic developer unit according to claim 6 in which said flexible drive means is a chain, and in which the means for connecting said oppositely =driven rollers to "the chain comprises a shaft, a sprocket mounted on the shaft and-engaging said chain, a driving roller-mounted on said shaft, and lever-means forenga'ging said driving roller alternately with said oppositely driven rollers.

References Cited in the file of this patent 

6. AN IMPROVED XEROGRAPHIC DEVELOPER UNIT COMPRISING: A NEARLY VERTICAL SUPPORT MEMBER; MEANS TO HOLD AN IMAGE SHEET, HAVING AN ELECTROSTATIC CHARGE IMAGE THEREON, ON SAID SUPPORT MEMBER; HORIZONTAL RUNWAYS EXTENDING ACROSS THE TOP OF SAID SUPPORT MEMBER; A NOZZLE, MOUNTED ON SAID RUNWAYS FOR MOVEMENT THEREALONG, FOR DISCHARGING A FLUID DEVELOPER ONTO AN IMAGE SHEET SUPPORTED ON SAID SUPPORT MEMBER; FLEXIBLE DRIVE MEANS EXTENDING ACROSS SAID SUPPORT MEMBER IN PARALLEL RELATION TO SAID RUNWAYS AND ENGAGED WITH SAID NOZZLE; A PAIR OF OPPOSITELY DRIVEN ROLLS; MEANS FOR ALTERNATELY CONNECTING SAID ROLLERS IN DRIVING RELATION TO SAID DRIVE MEANS TO MOVE SAID NOZZLE ACROSS THE TOP OF SAID SUPPORT MEMBER AND DISTRIBUTE FLUID DEVELOPER ACROSS THE ENTIRE SURFACE OF SAID SHEET; A RESERVOIR TROUGH FOR STORING A SUPPLY OF A FLUID DEVELOPER, DISPOSED AT THE BOTTOM OF SAID SUPPORT MEMBER IN POSITION TO RECEIVE AND STORE EXCESS DEVELOPER FLOWING DOWNWARDLY 